As is well known, in the naval sector, for the setting of the position of ships or oil recovery platforms, conventional anchors and the corresponding chains that attach the anchor to the ship or to the platform, are used for the setting of the position of ships or oil recovery platforms. Said chains are formed by means of links that connected together form sections of a specific length, and said sections are connected by means of connecting shackles with different shapes.
The chain thus formed is released and tightened by means of a pulley-capstan type mechanism, such as a drum, upon whose surface said chain in question and specifically the links that form it rest and slide.
To facilitate the movement of releasing and tensing or tightening the chain, the surface of the drum has the corresponding hollows or indentations that have a shape similar to that of the link itself of the chain.
On the other hand, connecting shackles tend to have a diametral section identical to that of the link, but with a different size and shape, and therefore to release and tighten the chain it is necessary that the shackle be always placed in a specific position with respect to the drum.
In the release and tightening of the main chain a guide-chain is also used, guide-chain that is not bound to comply with the specific resistance conditions of said main chain, fastening said guide-chain by means of a shackle in such a way that when the release and/or tightening of the main chain has taken place, it is necessary that the guide-chain be released from the main chain, by means of the opening of the connecting shackle, an operation that is not simple in most cases.